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Journal Article

Advances in real-time phase-contrast flow MRI using asymmetric radial gradient echoes.

MPS-Authors
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Untenberger,  M.
Biomedical NMR Research GmbH, MPI for Biophysical Chemistry, Max Planck Society;

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Voit,  D.
Biomedical NMR Research GmbH, MPI for Biophysical Chemistry, Max Planck Society;

/persons/resource/persons59192

Joseph,  A. A.
Biomedical NMR Research GmbH, MPI for Biophysical Chemistry, Max Planck Society;

/persons/resource/persons136471

Roeloffs,  V. B.
Biomedical NMR Research GmbH, MPI for Biophysical Chemistry, Max Planck Society;

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Merboldt,  K. D.
Biomedical NMR Research GmbH, MPI for Biophysical Chemistry, Max Planck Society;

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Schätz,  S.
Biomedical NMR Research GmbH, MPI for Biophysical Chemistry, Max Planck Society;

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Frahm,  J.
Biomedical NMR Research GmbH, MPI for Biophysical Chemistry, Max Planck Society;

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Supplementary Material (public)

2155763-Suppl-1.mp4
(Supplementary material), 174KB

2155763-Suppl-2.mp4
(Supplementary material), 3MB

Citation

Untenberger, M., Tan, Z., Voit, D., Joseph, A. A., Roeloffs, V. B., Merboldt, K. D., et al. (2016). Advances in real-time phase-contrast flow MRI using asymmetric radial gradient echoes. Magnetic Resonance in Medicine, 75(5), 1901-1908. doi:10.1002/mrm.25696.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0026-CE5E-0
Abstract
Purpose: To provide multidimensional velocity compensation for real-time phase-contrast flow MRI. Methods: The proposed method introduces asymmetric gradi- ent echoes for highly undersampled radial FLASH MRI with phase-sensitive image reconstruction by regularized nonlinear inversion (NLINV). Using an adapted gradient delay correction the resulting image quality was analyzed by simulations and experimentally validated at 3 Tesla. For real-time flow MRI the reduced gradient-echo timing allowed for the incorporation of velocity-compensating waveforms for all imaging gradients at even shorter repetition times. Results: The results reveal a usable degree of 20% asymme- try. Real-time flow MRI with full velocity compensation elimi- nated signal void in a flow phantom, confirmed flow parameters in healthy subjects and demonstrated signal recovery and phase conservation in a patient with aortic valve insufficiency and stenosis. Exemplary protocols at 1.4–1.5 mm resolution and 6 mm slice thickness achieved total acquisition times of 33.3–35.7 ms for two images (7 spokes each) with and without flow-encoding gradient. Conclusion: Asymmetric gradient echoes were successfully implemented for highly undersampled radial trajectories. The resulting temporal gain offers full velocity compensation for real-time phase-contrast flow MRI which minimizes false- positive contributions from complex flow and further enhances the temporal resolution compared with acquisitions with symmetric echoes.